David Peters's website – homebrew, coffee roasting, and more!

Who doesn’t enjoy simple geometry and spreadsheets? I made my own segment calculation spreadsheet just to get a better understanding of segmented turning. I’m not doing anything particularly complex so it was a fun little undertaking.

Here’s a link to the spreadsheet with some inner and outer radii already filled in. Feel free to make a copy of it (in the File menu) for your own project!

The inner and outer radii that you determine from your profile drawing go right into the spreadsheet. I should clarify that the inner radius does not determine the inside face of the segment, it is where the inside wall of your vessel will be. As you can see from the drawing, there is some extra material between the inside faces of the segments and the vessel. So you should notice that your calculated segment widths are a touch wider than the vessel wall thickness.

Inner and Outer radius determination

How the two radii and your angle α determine the segment’s dimensions

Sample spreadsheet output

Like many Imperial system users, I can easily “think” in inches but prefer accurate measurements in metric, so I have the spreadsheet inputs in inches and its outputs in both inches and millimeters.

I’ve also included a “Done?” column so that you can track your progress on a printed copy.

Jerry Bennett’s Wedgie Sled is a wonderfully simple and elegant solution to the problem of cranking out trapezoids for segmented turning. If you’re not familiar with his idea, visit his site and watch his video series.

The only hard part is what to do about setting the angle between the two fences; here are a few options:

Buy angle setup blocks – Jerry has them available but they are expensive!

Use a digital protractor – I tried iGaging’s protractor but it’s not accurate enough for this application. A resolution of 1/2 degree just isn’t good enough.

Make your own – but how??

The problem with making your own is that the angle temple needs to be quite accurate! The template’s error will be compounded by each segment in your ring; this is the basis for the “5-cut test” for squaring up a table saw miter fence.

The route I went with was to use machinist’s setup blocks to create my wedgie sled angle templates. I got this cheap set off of Amazon, whose smallest angle is 0.25°, and biggest is 30°. One can set up a wide variety of angles by stacking up two or more blocks.

Making the Template

I made my template out of a 3/4″ thick piece of MDF, although in the photos below I have the cut setup demonstrated with a piece of plywood.

The goal is to make a triangle with one angle being 360/n, where n is the number of segments in your ring. I was doing 16 segment rings so my n was 22.5°. And if you dust off your High School geometry, a little application of like triangles will show you that the angle between the two wedgie fences equals the included angle of each segment – very simple!

In the photos below I have three stacked angle blocks to get my cut: 20°, 2°, and 0.5°. It’s very important work off of a clean edge so that no fuzzies throw off your work. Here was my sequence:

Cut one edge of the board to clean it up

Rotate the board 90° clockwise so that the clean edge is against the miter fence – Take another light cut to clean up that edge

Add the angle blocks, creating as wide of a triangle as you can.

Take your time with setting up this cut! Be extra sure that your clamping mechanism doesn’t move the work.

Extra credit can be earned by “squaring up” the triangle – making its two short ends parallel so that you can set up your wedgie sled fairly square to the blade. To do this, I used a half-angle setup, 11.25° and a little square. If your wedgie sled is skewed a bit, your pieces will still have perfectly accurate sides but the inside and outside faces will be skewed a bit.

Setting up a 22.5° cut

Closer detail of the setup

Squaring off the end of the template with an 11.25° angle

Squaring up the other end of the template

Results

Using the template block is pretty easy, just smush your fences against it and tighten them up! The other photos are my rings, all of which were one-shot affairs: all the segments were cut & glued in one sequence. No half-rings or sanding needed.

Inspired by my friend Dominick’s attempt at a Turbo Oven-powered Drum Roaster I thought I’d build my own. While I appreciate the simplicity of my Stir Crazy base I’ve never been happy with the consistency of roasts; by its very nature it just can’t stir the beans around to evenly roast them.

In his version, Dominick talked about a long roast time of about 20 minutes. I figured that was due to heat loss through the sides of the enamel pot used for the base. So in my version I’ve made an insulated base which looks to have solved that problem.

Here’s a video I shot going over the roaster, it also includes some clips of it running.

Base

Wooden base showing inside wall mating surface

Mating surface for outside wall

Walls attached to base, bushing holes drilled

Brass bushing taped into place

Inside view of bushing

The base is made out of two aluminum walls fastened onto a wooden base. I turned the base on my lathe, making a tenon around the circumference that the two walls seat against. There is about 1″ is space between the walls.

The inside diameter is about 9.5″, enough to house the drum I’m using. The height of the walls needs to be high enough to not only house the drum (plus a reasonable gap on the bottom for clearance) but also high enough to clear the “nose” of the turbo oven. I forgot this second consideration and was only able to use the smaller of the two drums I bought. The walls are long strips of 0.025″ aluminum riveted to make loops. I used small #4 wood screws to secure them to the base.

Insulation is provided by glass fiber insulation. It doesn’t seem to mind the heat from coffee roasting.

Bearings for the drum rod are two flanged bronze sleeve bushings, 3/8″ in inner diameter. Because I’m using 1/4″ square rod, I needed something with a slightly bigger inner diameter to house the rod. And nicely enough, 0.25 x 1.414 is roughly equal to 0.325. I made sure to buy bearings with a flange to make them easier to mount in the walls. I only then have to secure one end.

Doesn’t the wood catch on fire?

I asked myself the same question! But no it has not, it has darkened a bit over 5+ roasts and oozed some sap. And after each roast I can smell pine resin, but that aroma has not made its way to the beans at all. The aluminum foil cover seems to help because it reflects the radiant heat produced by the Turbo Oven’s halogen light.

But with that said, when it comes time to re-make the base I will attempt an all-metal construction. And I have moved a fire extinguisher to my coffee roasting station just in case!

Drum and Rod

I bought two coffee drums off of eBay for this prototype because I didn’t know what size would work the best. Here is the listing, but in case that stops working they are each 18cm long with diameters of 14cm and 12cm. I’ve only ever used the 12cm drum because the 14cm drum doesn’t fit underneath the turbo oven.

The drums have a 0.6cm^2 square drive hole, which is pretty darn close to 0.25″ (6.35mm). The rod fit in there right away without any filing. However the holes were out of axial alignment so I had to file one of them on the corners to “rotate” it a bit to allow the shaft to slide all the way through.

Speaking of the shaft, it is a 1/4″ square solid stainless steel rod from Home Depot. I can’t find it on their site right now or I’d provide a link. Here is a similar product from Speedy Metals.

Motor

Roaster with old, noisy ice cream maker motor

This prototype has already seen three iterations of the motor!

Ice Cream Maker Motor

The first was off of an ice cream maker. It worked OK but was quite loud making it difficult to hear the cracks. (I also have not-great hearing, picking out details from background noise is difficult.) However, one positive for this motor was that its drive shaft was designed to accept a 1/4″ square rod! Another good thing about the motor is that it came from a $10 thrift store find so it didn’t require any eBay’ing.

4W Gear Motor

Version two has me using a 4W, 35RPM synchronous gear motor. These things are all over eBay and about about $10; here’s one listing. Be sure that the one you’re looking at is rated for 110V or 120V, there are also 12V models out there.

I have two of these little motors, one fixed to go clockwise and another which will randomly choose a direction when started (this is normal). We’ll call the former CW and the latter CW/CCW, because that’s what their labels have.

In a test run with 16oz of greens the CW/CCW motor had great difficulty starting out and needed a push. Not much more was needed to stall it, either. The CW motor worked a lot better, still needing a push to get started but it would not stall out on its own. As this writing I have a 14W motor on its way and will try that out and update this post when it arrives.

My first real roast with the 4W, CW motor worked really well but I only used 14oz of beans. It stuttered a bit while starting but once going worked the whole time. Roast #2 used 16 oz of greens and the motor would not start spinning until given a little help; but it at least ran the whole time without stopping.

14W Gear Motor

The third motor is a lot more powerful and should be the final one for this roaster. Here’s an eBay link, but if that doesn’t work for you look for a “14W 30RPM 110V synchronous gear motor”. It should be about $15 shipped.

While the motor’s description said it has a 6mm output shaft it’s actually 7mm so it immediately worked with the flexible coupler mentioned below.

The motor is reversible, so it has three electrical connections. This video shows a little more detail into how to wire it up, but the gist is that one AC lead goes into the middle and the other lead goes into one of the side connections. To change rotational direction use the opposite side. There’s no polarity with AC.

This motor, like the 4W, is close to silent in operation but has tons of power. It easily turned 16oz of greens, and I was unable to stop the drum with my hand.

It has four threaded bolt holes in its flange, M5-0.8.

Drive Shaft Coupling

While using a square bar for the drive shaft made it easy to mount onto the drum it made it a lot less easy to attach to the motor.

So I gripped the bar in my chuck’s pin jaws and filed the end of the square bar down to round.

Now I can couple the shaft to the motor. The motor has a 7mm shaft, and I now have a 6.35mm shaft, so I used a flexible coupler to join the two. I went with a flexible one because I know that none of my work is close to perfectly square or aligned. This lets the motor and shaft rotate in peace with the flexible coupler taking out the slack.

Detail of motor

Shaft mounted in coupler

Rounded shaft end

The motor is simply screwed to a T-shaped plywood stand. The above photos show the 4W motor but I used the same stand for the 14W motor.

Usage

Pre-heat the unit with the drum in place, slid onto the shaft and in the vessel. Make sure drum door is pointed upward.

Add beans and replace the turbo oven, set for perhaps 460F.

When 1C comes around, lower the heat to around 440 in order to avoid a rolling 2C

The end of the roast is still kind of awkward. Turn off drum, remove turbo oven, and then pull out the motor and shaft leaving the drum in hand. Now open the drum door and dump beans into cooling vessel

It’s not too different of a process as compared to my Stir Crazy, but is definitely less user-friendly when it comes to removing the beans from the device.

Results

I’ve been getting very good, consistent batches out of this machine. The drum’s agitation of the beans also does a better job of removing chaff than the stir crazy, my beans are very clean. I did struggle with over-roasting when I used the loud ice cream maker motor because the light 2C snaps were hard to pick out. But my last batch with the quiet synchronous motor was right on target because those first 2C snaps were easy to hear.

I’ve had my battery-powered 40V Ryobi mower (model #40108) for a year now and have been pretty happy with it. However the last time I used it the damn thing would randomly shut off while mowing. At the time there didn’t seem to be any rhyme or reason to the problem such as heavy grass or a weak battery which was reading 2/4 bars. I threw the battery into the string trimmer and it worked great.

So I took the lovely slime-green plastic cover off to see if there was anything obviously wrong. My hopes were low because I figured the mower would consist of a motor and control board.

Simple mower internals

Sure enough nothing looked wrong such as a leaking capacitor on the control board. But while putting it back together I noticed a kill switch I had never noticed before! It’s located by the handle hinge, ensuring that the mower will only run while the handle is in the folded-out position.

This little switch was flopping around in its hole because one of the spring clips on the backside was broken probably while I was removing that slime-green plastic cover. When the handle is folded out the switch is depressed, closing the circuit allowing the mower to run.

If you take a close look at the interaction between the switch and handle, it is not a precision operation. Due to the position of where the switch happens to be, the handle bumps into it, hopefully depressing it. Here’s the root cause of my problem: The mower’s frame had loosened up over time, allowing the frame to rack from side-to-side during turns. This racking let that little switch spring back up, opening the circuit and stopping the mower.

And thankfully the solution was to tighten these two T25 frame bolts, located right above the rear wheels.

Keep these bolts tight

And as a footnote, I bypassed that dumb switch just to avoid this kind of nonsense in the future. The connection was wrapped up with electrical tape after these photos were taken.

I’ve had my grinder on a Harbor Freight tool cart for the past year. I don’t have any more bench space in my shop so a mobile solution was all I had left. Plus skinning the sides with tools works pretty well and its nice having some shelf space.

Gouges on the left, scrapers on the right, with skews, parting tools, and a drill on back. It’s nice being able to put my grinder and tools right where I want them while turning and then tuck them away when doing something else.

However the lower shelves are only moderately useful because they’re short and deep, and they also fill up with chips. I couldn’t find a cheap (say $100 or less) tool cabinet with drawers all the way down and a solid top, so I was planning on just building a small two-drawer box to sit in the bottom space.

So off I went to Menard’s to get plywood, drawer slides, and pulls. On a whim I checked out their tool storage area and found a pretty damn good cart! It’s just wide enough to accommodate the Tormek jig arms and the price was right.

I re-used the tool holders but did make a new top from some 2x material. Some drawer dividers and I was ready to go! It holds much more than the old cart and should do a better job of keeping the chips out.

The thin profile of Veritas’ Striking Knife makes it pretty versatile but at the same time hard to sharpen. It’s very small so there’s little bevel to “feel” for and the blade material is bendy so it’s hard to keep in the exact same orientation while sharpening.

Consequently over time mine will loose its nice pointed end and flat sides and it can’t reach into tight corners. To help me re-establish a nice flat bevel I use a really simple “jig”, just a scrap of wood with two 25° slots cut into it.

The jig then holds the marking knife up against the flat side of my CBN wheel. The 220-grit finish from the wheel isn’t great so I then finish up with my usual honing routine.

This slot-in-a-block-of-wood type jig could be used against a normal bench grinder (front of wheel of course), belt sander, or even to hold the knife for hand-sharpening on stones.

For the purpose of woodturning it seems like the fineness of the edge doesn’t matter a whole lot. While the burr looks very nasty, and would be bad to have on a smoothing plane iron, it will get immediately knocked off in a woodturning project.

Introduction

Over time the outfeed table on my Rikon 25-210H worked its way out of adjustment, gradually creeping its way close to the cutterhead. I found out about this one day by the one cutter slamming into the table when I turned on the machine. So I was able to move the table back out of the way by turning its parallel arms but over time the table moved around more and more.

Looking at the Jet’s version of this machine (JJP-12HH), I saw that the outfeed adjustment arm also serves to lock it in place against the front cover. So I ordered the three parts from eReplacementParts that would give me that:

When the parts arrived I decided to start from scratch on tuning up the jointer tables, loosening the hinge adjustment screws thus throwing away the factory adjustment plus the work I had done. I wasn’t very confident in how aligned the tables were so I wasn’t losing much.

Terms Used

Pitch

Rotation of a table about the short axis of the machine. Right/left ends are up/down.

Roll

Rotation of a table about the long axis of the machine. Front/back sides are up/down.

Twist

Rotation involving both pitch and roll. One corner is off from the others.

Stop Bolts

The two bolts that each table stops on when closed.

Hinge Screws

The four grub screws in each hinge that control its orientation

Hinge Bolts

The three bolts in each hinge that secure it to the frame

(pitch and roll are aeronautic terms, they make it easier for me to visualize this stuff)

Tools

I have both the 38” and 50” straight edges from PeachTree and while the 38” model works OK the fact that the 50” lays across almost the entire table makes infeed adjustment a lot easier.

General Tips

Lock Down Levers and Stop Bolts

A smooshy feel when tightening means that the stop bolts are uneven; the “smoosh” is from the table flexing down to meet the top of both bolts. If you have the bolts even then you will experience a nice firm feel when tightening the lever.

Adjust the bolts by hand and with the table down. Turn one bolt to move the table up/down and then move the other bolt to just touch the table.

There are two stop bolts per table, with the locking rod in between them. There are two in order to provider a wider, more stable platform for the table to rest on. They do not participate in changing the pitch of either table; that is the job of the hinge levelling screws. After making changes to the levelling screws both stop bolts should be brought into equal contact with the table.

When you are ready to lock the stop bolts down, do so with the table locked down. This will help prevent the bolts from turning as you tighten the lock nuts down. It helps to have two 13mm wrenches here as there isn’t a lot of space for a crescent wrench to fit into.

Tightening the lock nuts has the effect of moving the bolts upwards a small amount. The thread’s backlash being taken up is my best guess as to why. In my experience you will have to tighten the bolts down by another ~20° to account for this.

Outfeed Table

If you are installing the outfeed adjustment lever you can rotate the parallel arm as-needed to clear the guard arm mount.

Loosen all grub screws before adjusting anything. There are two on the parallel arm and four on the lift rods.

“Reset Button” Sequence

Outfeed

Move infeed table down to take it out of the equation. You don’t want your straight edge resting on it.

Back out all four leveling screws until they are loose.

Tighten down hinge bolts

Loosen all the grub screws to allow the outfeed table to be freely adjusted using its parallel

Using the parallel arm try to adjust the outfeed to its ideal height, i.e. where the cutters just scrape your straight edge. Work first on the back edge, closest to the hinge. Note: it’s advise to not tune the table such that the Top Dead Center is at the ideal height. Give yourself some wiggle room should the outfeed table settle lower.

If you are able to reach ideal height in back, move onto step 6.

If you are not able to get the ideal height, i.e. the outfeed table is too low then you will need to raise it a bit via the hinge adjustment screws. Adjust them evenly, say ¼ turn each.

Again use the outfeed level to get the ideal height in back. If needed raise the table more via the hinge screws.

Now adjust the stop bolts to get the front of the table to the idea height.

This will most likely throw off the adjustment in back. Use the lever to regain your ideal height in back. This will mostly likely throw off your height in front, fix that via the stop bolts.

When you are done tighten all the grub screws on the outfeed table.

Infeed

Loosen the hinge leveling screws and tighten down the hinge bolts

Adjust the infeed table to its uppermost position such that it is even-ish with the outfeed table

At this point there shouldn’t be a lot of roll, just pitch to adjust for.

Attack the pitch first, adjusting the hinge screws in left/right pairs. For a gap of around 1/16”, start with pretty small turns of the screws, about ⅛ of the way around.

Measure in the back side first by the hinge, noting which side has a bigger gap.

Adjust the infeed table’s height to zero in on it being level with the outfeed table. Raise it such that it just contacts your straight edge at some point, either left or to the right.

Now check the front side, adjusting the stop bolts to match the roll between the outfeed and infeed tables. Another way to think about this is that your goal here is to have your straight edge’s contact with the infeed table the same in both front and back. It won’t be laying flat (unless you’re lucky) but the gaps and contact spots should at least be in the same areas.

Now note your gaps which will dictate your next round of adjustment. When you overshoot, and move the gap to the opposite end, back off the screws you just touched rather than tightening the screws by the new gap. This minimizes the variables in play.

Ideally you will be able to get things adjusted such that your 0.001” gauge won’t fit under the entire length of the table in both front and back; good luck with that 🙂

I put together a (too long) view on the process which also includes my thoughts on the product after messing around with it so much.

To summarize, setting the outfeed table is simpler than the infeed because it has fewer variables:

Outfeed:

Match the cutter head’s height

Match the cutter head’s roll

Infeed:

Match the outfeed’s height

Match the outfeed’s pitch

Match the outfeed’s roll

Front Cover Bracket Screw Hole Marking

I used a dowel marker pin over the bracket screw to mark where the hole should be drilled in the front cover. With the marker pin in place I positioned the cover about where it should go and then struck it with a rubber hammer.

I just got Jet’s 2HP cyclone dust collector as an upgrade from Grizzly’s 2HP canister unit. My main driver was to get a more quiet dust machine with a side benefit of it being easier to empty. So while I had both machines on hand I measured their sound levels and air volume throughput.

The purpose of this post is not only to compare the two machines but also to give a little more real world data on the sound levels produced by dust collectors as opposed to what the manufacturers publish.

Open Test

My first test put the machines out in the open with a short length of 4″ hose to constrict flow a bit. I stood with the sound meter from where the photo was taken, about 10 feet away.

Grizzly: 86 dBA, 1065 CFM

Jet: 82 dBA, 1070 CFM

The Grizzly’s sound level was pretty close to the published 83-85 dBA level. The Jet’s number was quite a bit higher than their published value of 76 dBA.

The air volume numbers were essentially the same, showing that the 4″ hose restricted them to the same volume.

Enclosed Test

Next I tested the dust collectors where they actually live, in this weird little room my basement has. It’s about 8′ x 8′ and is where the water main comes through the floor. As a woodworker it serves me pretty well by giving me a plash to stash a noisy machine.

On this test I measured the sound levels from about 15′ away next to my lathe. This is where I will spend a lot of time with the collector running while sanding or turning dry wood so I was interested to see what my ears would be subjected to.

As for airflow I measured the flow at my lathe’s dust hose and my jointer’s dust hose. Each of these machines are at the end of the two branches of my dust system.

Grizzly: 76 dBA, Lathe = 550 CFM, Jointer = 500 CFM

Jet: 70 dBA, Lathe = 550 CFM, Jointer = 532 CFMThe two jointer numbers are not the same because the machines have different inlet locations and therefore force a different shape in the hose hooked up to them. The Jet’s inlet is higher up so I was able to reduce the severity of the bends which netted me 30 more CFM. The lathe piping run kept the same shape.

I was happy to note that the Jet’s lower noise level is very noticeable from my lathe area. In fact the whooshing noise from the dust hood is pretty much louder than the actual dust collector.

This past weekend I assembled my new dust collector, Jet’s 2HP cyclone unit. The whole process took about two hours, most of which was spent getting the “head” (motor/impleller) mounted onto the frame. That part, when done according to the instructions was honestly hard to do.

As you can see in the photo I used my “shop crane”, a Harbor Freight 1-ton model, to lift the head. Unfortunately the legs of the shop crane did not allow the cyclone’s frame to be positioned directly underneath the head… they are about the exact same width as the halves of the frame. So I tipped the two parts towards each other and got them bolted up. This wasn’t an elegant or safe operation but it worked. After it was bolted up I was able to tip the dust collector back upright.

If I had to do this over again I would still use my shop crane to lift the head, but I would not have first assembled the two frame halves together. I would have left them separate and bolted them onto the head while in the air. Then I would have lowered the dust collector to a horizontal position cradling the head on some the styrofoam it was packed in, and then assembled the rest of the frame. Tilting it back up could have been assisted by the shop crane.